In a liquid crystal display device, a classification based on an operating mode for liquid crystal molecules includes a phase change (PC) mode, a twisted nematic (TN) mode, a super twisted nematic (STN) mode, an electrically controlled birefringence (ECB) mode, an optically compensated bend (OCB) mode, an in-plane switching (IPS) mode, a vertical alignment (VA) mode, a fringe field switching (FFS) mode and a field-induced photo-reactive alignment (FPA) mode. A classification based on a driving mode in the device includes a passive matrix (PM) and an active matrix (AM). The PM is classified into static, multiplex and so forth, and the AM is classified into a thin film transistor (TFT), a metal insulator metal (MIM) and so forth.
The device is sealed with a liquid crystal composition. Physical properties of the composition relate to characteristics in the device. Specific examples of the physical properties in the composition include stability to heat or light, a temperature range of a nematic phase, viscosity, optical anisotropy, dielectric anisotropy, specific resistance and an elastic constant. The composition is prepared by mixing many liquid crystal compounds. Physical properties required for a compound include high stability to environment such as water, air, heat and light, a wide temperature range of a liquid crystal phase, small viscosity, large optical anisotropy, large dielectric anisotropy, a suitable elastic constant and good compatibility with other liquid crystal compounds. A compound having high maximum temperature of the nematic phase is preferred. A compound having low minimum temperature in the liquid crystal phase such as the nematic phase and a smectic phase is preferred. A compound having small viscosity can shorten a response time in the device. A compound having large optical anisotropy can decrease cell thickness in the device, and therefore can shorten the response time. A compound having large positive or negative dielectric anisotropy is preferred for driving the device at low voltage. A compound having good compatibility with other liquid crystal compounds is preferred for preparing the composition. The device may be occasionally used at a temperature below freezing point, and therefore a compound having good compatibility at low temperature is preferred.
Many liquid crystal compounds have been so far prepared. Development of a new liquid crystal compound has been still continued. The reason is that good physical properties that are not found in conventional compounds are expected from a new compound. The reason is that the new compound may be occasionally provided with a suitable balance regarding at least two physical properties in the composition. Compounds as described below are reported. However, in compounds (A) and (B), a melting point is high, and the compatibility with other liquid crystal compounds is not sufficiently high. Moreover, compounds (C), (D) and (E) do not exhibit sufficiently large negative dielectric anisotropy.
JP H10-236992 A discloses compound (A) on page 36.

WO 2015/129412 A discloses compounds (B-1) and (B-2) on page 71 and page 73, respectively.

WO 2002/055463 A discloses compound (C-1) on page 27.

JP 2015-174864 A discloses compound (D) on page 26.

EP 1223210 A discloses compound (E) on page 16.
